无效使用未定义类型&储存空间未知 [英] invalid use of undefined type & storage size unknown

问题描述

我正在尝试将某些功能移到 c 项目中的单独文件中.

I am trying to move some functions to separate file in c project.

我用

#ifndef _UTIL_H
#define _UTIL_H

#include <signal.h>
#include <termios.h>
#include <time.h>

...

extern struct timeval tv1, tv2, dtv;

void time_start();

long time_stop();

我用

制作了 util.c 文件

#include "util.h"

...
struct timeval tv1, tv2, dtv;

void time_start() { gettimeofday(&tv1, &timezone); }

long time_stop()
{
    gettimeofday(&tv2, &timezone);
    dtv.tv_sec = tv2.tv_sec - tv1.tv_sec;
...

在我拥有的cmake中

in cmake I have

add_executable(mpptd mpptd.c util.c)

在编译过程中出现以下错误

and I get the following errors during compile

[build] ../settings/daemons/util.c: In function ‘time_stop’:
[build] ../settings/daemons/util.c:14:8: error: invalid use of undefined type ‘struct timeval’
[build]      dtv.tv_sec = tv2.tv_sec - tv1.tv_sec;
[build]         ^

和

[build] ../settings/daemons/util.c: At top level:
[build] ../settings/daemons/util.c:7:16: error: storage size of ‘tv1’ isn’t known
[build]  struct timeval tv1, tv2, dtv;
[build]                 ^~~

这里有什么问题?为什么要存储大小"?错误发生的时间比未定义类型"晚错误?谁不早点去?

What can be wrong here? Why "storage size" error goes later than "undefined type" error? Whouldn't it go earlier?

推荐答案

struct timeval 在sys/time.h中定义.您需要将其包括在内.

struct timeval is defined in sys/time.h. You'll need to include that.

#ifndef _UTIL_H
#define _UTIL_H

#include <signal.h>
#include <termios.h>
#include <time.h>
#include <sys/time.h>

...

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